Here is the full list of all 30 Downward achievements.
Perform 500 wall-runs.
Get 10 Gold medals in the Challenges.
Perform 500 slingshots.
Perform 500 double jumps.
Perform 500 wall-jumps.
Get a Gold medal in the Challenges.
Obtain 2000 Skypieces.
Unlock all Pursuance skills.
Unlock all Wisdom skills.
Unlock all Meditation skills.
Unlock all Endurance skills.
Unlock all Insight skills.
Obtain 1000 Skypieces.
Gather 50 Dry Artifacts.
Obtain 500 Skypieces.
Survive your own recklessness.
Buy all the upgrades of the Old Man's Room.
Build four different rooms in the Merchant's Lair.
Sell 15 items to the Merchant.
Die from a Cactus.
Gather 25 Dry Artifacts.
Obtain the Slingshot Artifact.
Sell 5 items to the Merchant.
Reach the temple on top of the cliff.
Obtain the Double Jump Artifact.
Die from a Drone explosion.
Exit the tutorial area.
Defeat your first golem.
Use the Mark for the first time.
Wake Up!